Recently, rechargeable secondary batteries are widely used as energy sources or auxiliary power devices of wireless mobile devices. In addition, secondary batteries are drawing great attraction as power sources of electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEV) and the like suggested as alternatives to solve air pollution caused by conventional gasoline vehicles, diesel vehicles and the like using fossil fuels.
Such a secondary battery is manufactured in a state in which an electrode assembly is mounted in a battery case together with an electrolyte solution. Depending on the manufacturing method employed, the electrode assembly is divided into a stack-type, a folding-type, a stack-folding type and the like. In the case of the stack type or stack-folding type electrode assembly, a unit assembly has a structure in which a cathode and an anode are laminated in this order such that a separator is interposed therebetween. In order to manufacture such an electrode assembly, manufacture of a unit electrode laminate having a bi-cell or full-cell structure is first required.
In order to manufacture a unit electrode laminate, a process for cutting an electrode sheet laminate, wherein two or more continuous electrode sheets in which an electrode active material is applied to one or both surfaces thereof are laminated, at an interval of unit electrodes is necessary. This cutting process is generally carried out by cutting the laminate using a cutter and a continuous feeding manner is commonly used.
The continuous feeding manner is a method in which a cutter synchronizes with the electrode sheet laminate and, at the same time, cutting is performed. In this manner, the electrode sheet laminate is continuously fed without stop, and the cutter moves together with it and repeats coating. As a result, the cutter moves in a movement direction of the electrode sheet laminate and performs cutting while it moves back and forth periodically at a predetermined distance.
However, the cutting using this continuous feeding manner secures suitable production efficiency when the electrode sheet laminate moves at a low rate, but problems of serious noise, great increase in abrasion and thus decrease in replacement time of the cutter occur at a region where the cutter cuts the electrode sheet laminate when a feeding rate of the electrode sheet laminate is high. As a result, there is a fundamental limit to increase of the feed rate, thus limiting production efficiency.
Accordingly, there is a need for development of novel cutting devices to solve these problems.